Dodaj token JWT w nagłówku

function getAllClients() {
const myHeaders = new Headers({
    'Content-Type': 'application/json',
    'Authorization': 'your-token'
});

return fetch('http://localhost:8080/clients', {
  method: 'GET',
  headers: myHeaders,
})

.then(response => {
    if (response.status === 200) {
      return response.json();
    } else {
      throw new Error('Something went wrong on api server!');
    }
  })
  .then(response => {
    console.debug(response);
  }).catch(error => {
    console.error(error);
  });
}

getAllClients();
Smiling Squirrel